The present invention relates to a fluid container, in particular a hydraulic tank for a motor pump unit.
In electrohydraulic vehicle steering systems, motor pump units are made use of which supply a hydraulic circuit with hydraulic fluid from a hydraulic tank. Restrictions in installation space and measures to reduce costs necessitate that the additional equalizing tanks for the hydraulic fluid which are commonly used and are located at an elevated point are dispensed with and that, instead, one-piece and at the same time small tanks are used. The high performance or output of the motor pump unit required in modern systems leads to an increase in volume flows of the hydraulic fluid which flows into the tank at a high velocity, the tank also including an equalizing volume filled with air. This may possibly entail a violent mixing of air and hydraulic fluid, which results in a foam formation. The air bound in the foam is then sucked in through the pump of the motor pump unit, and the efficiency of the system will decrease drastically.
In order to counteract these problems, DE 10 2004 015 960 A1 already describes a hydraulic tank in which a return flow from the hydraulic circuit and a hydraulic flow delivered through a pressure control valve of the pump are first deflected by flow guiding elements arranged in the tank before they reach an accommodation chamber for the hydraulic fluid. This is intended to stabilize the inflowing hydraulic fluid and to avoid foaming up.
In contrast, the invention provides a fluid container which is based on an entirely novel operating principle, as a result of which a foam formation can be completely avoided even in the case of very high performance densities.